1. Field of the Invention
This invention relates to the general field of gelled-electrolyte storage batteries, and more particularly to a perforated electrolyte retainer which allows such battery cells to be mounted in a horizontal position.
2. Description of the Prior Art
Gelled electrolyte has long been used for lead-acid batteries intended for applications requiring an immobilized electrolyte. It is also frequently used for its gas recombinant properties. The properties of such batteries, and of the common compositions of gelled electrolytes using various proportions of silica or other gelling agents, are well known in the industry, and consequently will not be further described herein.
Sealed gas-recombinant gelled electrolyte cells are often mounted in racks or modules that are stacked and connected to assemble a stationary battery of the required voltage and capacity. Space and access considerations frequently dictate that the cells be placed in a horizontal position; that is, with the open space between the electrode plates and the container cover lying horizontal to the plates, rather than above them. Unfortunately, the horizontal orientation allows the dried electrolyte at what had originally been the top of the cell to crumble along the fissures created during hardening, separate from the plates, and fall into the open space toward the container cover. This process is progressive over discharge/charge cycles, even for low discharge "float" cycling. Excessive electrolyte separation from the plates will eventually decrease battery performance and useful life.
A battery specifically designed for horizontal mounting is disclosed in U.S. Pat. No. 4,894,300. The battery uses a filler material, such as an air-hardening polyurethane foam, to fill between the cover and the electrolyte over about half of the open space, that half being specifically the one surrounding the positive terminal post, with the space surrounding the negative post left open to collect gases and relieve internal gas pressure through a regulator valve. An angled partition holds the foam in the proper shape until it hardens. Although the patent describes the purpose of the foam as preventing liquid sulfuric acid from accumulating between the cover and the gel layer, it will inherently prevent gel crumbling in the filled space. The open space surrounding the negative post will still experience crumbling and separation from the plates. Further, as described in its specification, the battery of U.S. Pat. No. 4,894,300 is properly mounted in only one horizontal configuration; that is, with the negative terminal directly over the positive.
The present invention treats the problem of gel crumbling and separation directly. Among the objectives sought to be achieved is a substantial reduction of surface crumbling of the gel to prevent separation from the electrode plates over the normal battery life. It is also an objective that the cells not be limited to a specific horizontal mounting position, and that any structure used to reduce gel crumbling be easily integrated into the battery manufacturing process.